Applications can be downloaded and installed on mobile computing devices. Applications can provide a wide variety of functions to users of mobile computing devices. To provide such functions, applications can request operations performed by one or more resources of the mobile computing device. For example, an application that has audio/video functions may request that an image or a video be displayed on the mobile computing device's display and that audio be output via a speaker or an audio output port of the mobile computing device. As different applications may provide different functionality to a user, the different applications may request different resources from the mobile computing devices upon which they are installed.